The present invention relates to electrical switches and more specifically to center-off floating contact switches.
Electric switches including an electrical contact which operates as a fulcrum with respect to a contact bridging member, the bridging member sliding over the fulcrum contacts and pivots thereabout to bring one end of the bridging member into contact with, or break contact with, a second electrode. Examples of such switches are described in U.S. Pat. Nos. 3,711,663 issued Jan. 16, 1973 to R. Sorenson, and 3,536,872 issued Oct. 27, 1970 to B. Gilardenghi.
One aspect of the present invention provides such a switch wherein platform means are provided on the fulcrum contact on the side of the fulcrum remote from the second contact. The platform means operates to support the bridging member intermediate its length with the end adjacent the second contact being unsupported and out of contact with the second contact, to thereby provide a stable center-off position.
Similarly, an electrical contact having spaced apart portions, respectively acting as first and second fulcrums, can be provided with platform means intermediate the first and second fulcrums. Second and third contacts can be provided respectively adjacent the first and second fulcrums on opposite sides of the fulcrum contact.
The fulcrum electrical contact preferably has an end surface which serves as the platform means and that surface has an edge serving as the operational fulcrum, in an instance in which only one fulcrum is required, or edges serving as the first and second fulcrums.
In a particularly preferred construction the first contact has a bent over end which defines a surface which serves as the platform means and an edge serving as the fulcrum, in an instance in which only one fulcrum is required, or edges as the first and second fulcrums.
As it will be preferred in some instances that the first and second fulcrums are equidistantly spaced from, respectively, the second and third contacts, the first contact will preferably comprise a portion more adjacent to one of the second and third contacts than the other of the second and third contacts and that the bent over end extends toward said other of the second and third contacts.
In other instances it will be preferred that the first and second fulcrums are not equidistantly spaced from, respectively, the second and third contacts.
The bridging member may be substantially planar over its length but may have a dimple therein or struck out abutments such as are disclosed in the aforesaid co-pending applications. In the case of having a dimple, the platform means, the fulcrum or the first and second fulcrum should have means adapted to accommodate the passing thereof.
The bridging member could have a convex surface such as disclosed in the aforesaid co-pending applications which contacts the fulcrum or the first and second fulcrums and the platform means but to ensure stability it would be highly desirable that the platform means comprised a concave surface to be contacted by said member. For reasons of convenience of manufacture the convexity-concavity is not preferred.
The bridging member may have an intermediate planar portion and upturned ends (when viewed in a particular disposition) such as disclosed in the specification of U.S. patent application Ser. No. 634,177. Such a bridging member is preferred since the advantages of a convex surface are obtained without the need for convexity.
In accordance with another aspect of the invention a switch may be used with one or more further switches in accordance with the present invention, or with switches such as described in the aforesaid copending applications, all operable by a common actuator.
Such arrangements are particularly advantageous in that they provide many alternative switching states. For example, by relatively offsetting the operational fulcrums of the respective switch assemblies, the sequence of pivoting and hence, switching as between the respective switching assemblies can be controlled.
While the above-mentioned platform means is not requisite to this further aspect of the invention, it is often desirable to use such platform means in that further switching positions may be provided. Further the relative positions of the respective lengths of the platform means of the various cooperating switching assemblies can be utilized to define the switching sequence.
In a particularly preferred construction, the first and second switchgear assemblies are side by side. The second switchgear contacts lie in a plane and the first contacts lie in spaced apart planes generally parallel to the plane in which the second contacts lie.